Walking and sitting create fundamentally different cognitive contexts. When you're moving, attention is divided—the interface competes with navigation, obstacles, other people. Detailed information becomes noise.

When you're stationary, attention capacity expands. The same detail that was overwhelming becomes useful. The interface should breathe with your movement—expanding when you stop, contracting when you go.

Same data, different presentation. Context determines the correct density.

The visualization shows this relationship directly: as velocity decreases, density increases. The weather card expands, revealing layers of information that were always there but hidden until the moment was right.

A good density transition takes approximately 800 milliseconds from signal detection to fully surfaced detail. The sequence is precise:

T+0ms: User begins to slow down. Velocity change detected.

T+200ms: System confirms intentional stop vs momentary pause.

T+350ms: UI begins expansion transition.

T+750ms: Transition completes, details fully visible.

T+800ms: User is stationary, reading comfortably.

Feels instant. Feels like the system read your mind. It didn't—it read your behavior and timed the response perfectly.

Density timing failures are immediately obvious. They create friction where flow should exist. The same interface becomes frustrating through mistiming alone:

These aren't design failures in isolation—they're timing failures. The information was correct. The presentation was correct. The moment was wrong.

Same interface, wrong moment = failure. The when matters as much as the what.

This is the heart of ambient computing. Surfaces rise when relevant. Details emerge when needed. Complexity settles when you're done. The interface breathes with you.

The pattern connects to the Latent Graph: behavioral prediction tells the system what you'll likely need. Density timing tells the system when to show it. Together, they enable anticipation.

Example: The system knows you approach the coffee shop at 5:47pm on Tuesdays (from the latent graph). The loyalty card surfaces at T-10 seconds (from density timing). Not after you arrive—before. Anticipation, not reaction.

Traditional approach: Arrive → open app → find loyalty card. Too late, already in line.

Timed approach: Walking toward shop → card rises automatically → ready when needed.

The difference is subtle but profound. One requires conscious effort. The other feels like the system understood your intent. Both show the same card—timing creates the magic.